drivers/iio/adc/ti-ads1100.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * ADS1100 - Texas Instruments Analog-to-Digital Converter
   4  *
   5  * Copyright (c) 2023, Topic Embedded Products
   6  *
   7  * Datasheet: https://www.ti.com/lit/gpn/ads1100
   8  * IIO driver for ADS1100 and ADS1000 ADC 16-bit I2C
   9  */
  10
  11 #include <linux/bitfield.h>
  12 #include <linux/bits.h>
  13 #include <linux/delay.h>
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/i2c.h>
  17 #include <linux/mutex.h>
  18 #include <linux/property.h>
  19 #include <linux/pm_runtime.h>
  20 #include <linux/regulator/consumer.h>
  21 #include <linux/units.h>
  22
  23 #include <linux/iio/iio.h>
  24 #include <linux/iio/types.h>
  25
  26 /* The ADS1100 has a single byte config register */
  27
  28 /* Conversion in progress bit */
  29 #define ADS1100_CFG_ST_BSY      BIT(7)
  30 /* Single conversion bit */
  31 #define ADS1100_CFG_SC          BIT(4)
  32 /* Data rate */
  33 #define ADS1100_DR_MASK         GENMASK(3, 2)
  34 /* Gain */
  35 #define ADS1100_PGA_MASK        GENMASK(1, 0)
  36
  37 #define ADS1100_CONTINUOUS      0
  38 #define ADS1100_SINGLESHOT      ADS1100_CFG_SC
  39
  40 #define ADS1100_SLEEP_DELAY_MS  2000
  41
  42 static const int ads1100_data_rate[] = { 128, 32, 16, 8 };
  43 static const int ads1100_data_rate_bits[] = { 12, 14, 15, 16 };
  44
  45 struct ads1100_data {
  46         struct i2c_client *client;
  47         struct regulator *reg_vdd;
  48         struct mutex lock;
  49         int scale_avail[2 * 4]; /* 4 gain settings */
  50         u8 config;
  51         bool supports_data_rate; /* Only the ADS1100 can select the rate */
  52 };
  53
  54 static const struct iio_chan_spec ads1100_channel = {
  55         .type = IIO_VOLTAGE,
  56         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
  57         .info_mask_shared_by_all =
  58             BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
  59         .info_mask_shared_by_all_available =
  60             BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
  61         .scan_type = {
  62                       .sign = 's',
  63                       .realbits = 16,
  64                       .storagebits = 16,
  65                       .endianness = IIO_CPU,
  66                        },
  67         .datasheet_name = "AIN",
  68 };
  69
  70 static int ads1100_set_config_bits(struct ads1100_data *data, u8 mask, u8 value)
  71 {
  72         int ret;
  73         u8 config = (data->config & ~mask) | (value & mask);
  74
  75         if (data->config == config)
  76                 return 0;       /* Already done */
  77
  78         ret = i2c_master_send(data->client, &config, 1);
  79         if (ret < 0)
  80                 return ret;
  81
  82         data->config = config;
  83
  84         return 0;
  85 };
  86
  87 static int ads1100_data_bits(struct ads1100_data *data)
  88 {
  89         return ads1100_data_rate_bits[FIELD_GET(ADS1100_DR_MASK, data->config)];
  90 }
  91
  92 static int ads1100_get_adc_result(struct ads1100_data *data, int chan, int *val)
  93 {
  94         int ret;
  95         __be16 buffer;
  96         s16 value;
  97
  98         if (chan != 0)
  99                 return -EINVAL;
 100
 101         ret = pm_runtime_resume_and_get(&data->client->dev);
 102         if (ret < 0)
 103                 return ret;
 104
 105         ret = i2c_master_recv(data->client, (char *)&buffer, sizeof(buffer));
 106
 107         pm_runtime_mark_last_busy(&data->client->dev);
 108         pm_runtime_put_autosuspend(&data->client->dev);
 109
 110         if (ret < 0) {
 111                 dev_err(&data->client->dev, "I2C read fail: %d\n", ret);
 112                 return ret;
 113         }
 114
 115         /* Value is always 16-bit 2's complement */
 116         value = be16_to_cpu(buffer);
 117
 118         /* Shift result to compensate for bit resolution vs. sample rate */
 119         value <<= 16 - ads1100_data_bits(data);
 120
 121         *val = sign_extend32(value, 15);
 122
 123         return 0;
 124 }
 125
 126 static int ads1100_set_scale(struct ads1100_data *data, int val, int val2)
 127 {
 128         int microvolts;
 129         int gain;
 130
 131         /* With Vdd between 2.7 and 5V, the scale is always below 1 */
 132         if (val)
 133                 return -EINVAL;
 134
 135         if (!val2)
 136                 return -EINVAL;
 137
 138         microvolts = regulator_get_voltage(data->reg_vdd);
 139         /*
 140          * val2 is in 'micro' units, n = val2 / 1000000
 141          * result must be millivolts, d = microvolts / 1000
 142          * the full-scale value is d/n, corresponds to 2^15,
 143          * hence the gain = (d / n) >> 15, factoring out the 1000 and moving the
 144          * bitshift so everything fits in 32-bits yields this formula.
 145          */
 146         gain = DIV_ROUND_CLOSEST(microvolts, BIT(15)) * MILLI / val2;
 147         if (gain < BIT(0) || gain > BIT(3))
 148                 return -EINVAL;
 149
 150         ads1100_set_config_bits(data, ADS1100_PGA_MASK, ffs(gain) - 1);
 151
 152         return 0;
 153 }
 154
 155 static int ads1100_set_data_rate(struct ads1100_data *data, int chan, int rate)
 156 {
 157         unsigned int i;
 158         unsigned int size;
 159
 160         size = data->supports_data_rate ? ARRAY_SIZE(ads1100_data_rate) : 1;
 161         for (i = 0; i < size; i++) {
 162                 if (ads1100_data_rate[i] == rate)
 163                         return ads1100_set_config_bits(data, ADS1100_DR_MASK,
 164                                                        FIELD_PREP(ADS1100_DR_MASK, i));
 165         }
 166
 167         return -EINVAL;
 168 }
 169
 170 static int ads1100_get_vdd_millivolts(struct ads1100_data *data)
 171 {
 172         return regulator_get_voltage(data->reg_vdd) / (MICRO / MILLI);
 173 }
 174
 175 static void ads1100_calc_scale_avail(struct ads1100_data *data)
 176 {
 177         int millivolts = ads1100_get_vdd_millivolts(data);
 178         unsigned int i;
 179
 180         for (i = 0; i < ARRAY_SIZE(data->scale_avail) / 2; i++) {
 181                 data->scale_avail[i * 2 + 0] = millivolts;
 182                 data->scale_avail[i * 2 + 1] = 15 + i;
 183         }
 184 }
 185
 186 static int ads1100_read_avail(struct iio_dev *indio_dev,
 187                               struct iio_chan_spec const *chan,
 188                               const int **vals, int *type, int *length,
 189                               long mask)
 190 {
 191         struct ads1100_data *data = iio_priv(indio_dev);
 192
 193         if (chan->type != IIO_VOLTAGE)
 194                 return -EINVAL;
 195
 196         switch (mask) {
 197         case IIO_CHAN_INFO_SAMP_FREQ:
 198                 *type = IIO_VAL_INT;
 199                 *vals = ads1100_data_rate;
 200                 if (data->supports_data_rate)
 201                         *length = ARRAY_SIZE(ads1100_data_rate);
 202                 else
 203                         *length = 1;
 204                 return IIO_AVAIL_LIST;
 205         case IIO_CHAN_INFO_SCALE:
 206                 *type = IIO_VAL_FRACTIONAL_LOG2;
 207                 *vals = data->scale_avail;
 208                 *length = ARRAY_SIZE(data->scale_avail);
 209                 return IIO_AVAIL_LIST;
 210         default:
 211                 return -EINVAL;
 212         }
 213 }
 214
 215 static int ads1100_read_raw(struct iio_dev *indio_dev,
 216                             struct iio_chan_spec const *chan, int *val,
 217                             int *val2, long mask)
 218 {
 219         int ret;
 220         struct ads1100_data *data = iio_priv(indio_dev);
 221
 222         mutex_lock(&data->lock);
 223         switch (mask) {
 224         case IIO_CHAN_INFO_RAW:
 225                 ret = iio_device_claim_direct_mode(indio_dev);
 226                 if (ret)
 227                         break;
 228
 229                 ret = ads1100_get_adc_result(data, chan->address, val);
 230                 if (ret >= 0)
 231                         ret = IIO_VAL_INT;
 232                 iio_device_release_direct_mode(indio_dev);
 233                 break;
 234         case IIO_CHAN_INFO_SCALE:
 235                 /* full-scale is the supply voltage in millivolts */
 236                 *val = ads1100_get_vdd_millivolts(data);
 237                 *val2 = 15 + FIELD_GET(ADS1100_PGA_MASK, data->config);
 238                 ret = IIO_VAL_FRACTIONAL_LOG2;
 239                 break;
 240         case IIO_CHAN_INFO_SAMP_FREQ:
 241                 *val = ads1100_data_rate[FIELD_GET(ADS1100_DR_MASK,
 242                                                    data->config)];
 243                 ret = IIO_VAL_INT;
 244                 break;
 245         default:
 246                 ret = -EINVAL;
 247                 break;
 248         }
 249         mutex_unlock(&data->lock);
 250
 251         return ret;
 252 }
 253
 254 static int ads1100_write_raw(struct iio_dev *indio_dev,
 255                              struct iio_chan_spec const *chan, int val,
 256                              int val2, long mask)
 257 {
 258         struct ads1100_data *data = iio_priv(indio_dev);
 259         int ret;
 260
 261         mutex_lock(&data->lock);
 262         switch (mask) {
 263         case IIO_CHAN_INFO_SCALE:
 264                 ret = ads1100_set_scale(data, val, val2);
 265                 break;
 266         case IIO_CHAN_INFO_SAMP_FREQ:
 267                 ret = ads1100_set_data_rate(data, chan->address, val);
 268                 break;
 269         default:
 270                 ret = -EINVAL;
 271                 break;
 272         }
 273         mutex_unlock(&data->lock);
 274
 275         return ret;
 276 }
 277
 278 static const struct iio_info ads1100_info = {
 279         .read_avail = ads1100_read_avail,
 280         .read_raw = ads1100_read_raw,
 281         .write_raw = ads1100_write_raw,
 282 };
 283
 284 static int ads1100_setup(struct ads1100_data *data)
 285 {
 286         int ret;
 287         u8 buffer[3];
 288
 289         /* Setup continuous sampling mode at 8sps */
 290         buffer[0] = ADS1100_DR_MASK | ADS1100_CONTINUOUS;
 291         ret = i2c_master_send(data->client, buffer, 1);
 292         if (ret < 0)
 293                 return ret;
 294
 295         ret = i2c_master_recv(data->client, buffer, sizeof(buffer));
 296         if (ret < 0)
 297                 return ret;
 298
 299         /* Config register returned in third byte, strip away the busy status */
 300         data->config = buffer[2] & ~ADS1100_CFG_ST_BSY;
 301
 302         /* Detect the sample rate capability by checking the DR bits */
 303         data->supports_data_rate = FIELD_GET(ADS1100_DR_MASK, buffer[2]) != 0;
 304
 305         return 0;
 306 }
 307
 308 static void ads1100_reg_disable(void *reg)
 309 {
 310         regulator_disable(reg);
 311 }
 312
 313 static void ads1100_disable_continuous(void *data)
 314 {
 315         ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
 316 }
 317
 318 static int ads1100_probe(struct i2c_client *client)
 319 {
 320         struct iio_dev *indio_dev;
 321         struct ads1100_data *data;
 322         struct device *dev = &client->dev;
 323         int ret;
 324
 325         indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
 326         if (!indio_dev)
 327                 return -ENOMEM;
 328
 329         data = iio_priv(indio_dev);
 330         dev_set_drvdata(dev, data);
 331         data->client = client;
 332         mutex_init(&data->lock);
 333
 334         indio_dev->name = "ads1100";
 335         indio_dev->modes = INDIO_DIRECT_MODE;
 336         indio_dev->channels = &ads1100_channel;
 337         indio_dev->num_channels = 1;
 338         indio_dev->info = &ads1100_info;
 339
 340         data->reg_vdd = devm_regulator_get(dev, "vdd");
 341         if (IS_ERR(data->reg_vdd))
 342                 return dev_err_probe(dev, PTR_ERR(data->reg_vdd),
 343                                      "Failed to get vdd regulator\n");
 344
 345         ret = regulator_enable(data->reg_vdd);
 346         if (ret < 0)
 347                 return dev_err_probe(dev, ret,
 348                                      "Failed to enable vdd regulator\n");
 349
 350         ret = devm_add_action_or_reset(dev, ads1100_reg_disable, data->reg_vdd);
 351         if (ret)
 352                 return ret;
 353
 354         ret = ads1100_setup(data);
 355         if (ret)
 356                 return dev_err_probe(dev, ret,
 357                                      "Failed to communicate with device\n");
 358
 359         ret = devm_add_action_or_reset(dev, ads1100_disable_continuous, data);
 360         if (ret)
 361                 return ret;
 362
 363         ads1100_calc_scale_avail(data);
 364
 365         pm_runtime_set_autosuspend_delay(dev, ADS1100_SLEEP_DELAY_MS);
 366         pm_runtime_use_autosuspend(dev);
 367         pm_runtime_set_active(dev);
 368         ret = devm_pm_runtime_enable(dev);
 369         if (ret)
 370                 return dev_err_probe(dev, ret, "Failed to enable pm_runtime\n");
 371
 372         ret = devm_iio_device_register(dev, indio_dev);
 373         if (ret)
 374                 return dev_err_probe(dev, ret,
 375                                      "Failed to register IIO device\n");
 376
 377         return 0;
 378 }
 379
 380 static int ads1100_runtime_suspend(struct device *dev)
 381 {
 382         struct ads1100_data *data = dev_get_drvdata(dev);
 383
 384         ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
 385         regulator_disable(data->reg_vdd);
 386
 387         return 0;
 388 }
 389
 390 static int ads1100_runtime_resume(struct device *dev)
 391 {
 392         struct ads1100_data *data = dev_get_drvdata(dev);
 393         int ret;
 394
 395         ret = regulator_enable(data->reg_vdd);
 396         if (ret) {
 397                 dev_err(&data->client->dev, "Failed to enable Vdd\n");
 398                 return ret;
 399         }
 400
 401         /*
 402          * We'll always change the mode bit in the config register, so there is
 403          * no need here to "force" a write to the config register. If the device
 404          * has been power-cycled, we'll re-write its config register now.
 405          */
 406         return ads1100_set_config_bits(data, ADS1100_CFG_SC,
 407                                        ADS1100_CONTINUOUS);
 408 }
 409
 410 static DEFINE_RUNTIME_DEV_PM_OPS(ads1100_pm_ops,
 411                                  ads1100_runtime_suspend,
 412                                  ads1100_runtime_resume,
 413                                  NULL);
 414
 415 static const struct i2c_device_id ads1100_id[] = {
 416         { "ads1100" },
 417         { "ads1000" },
 418         { }
 419 };
 420
 421 MODULE_DEVICE_TABLE(i2c, ads1100_id);
 422
 423 static const struct of_device_id ads1100_of_match[] = {
 424         {.compatible = "ti,ads1100" },
 425         {.compatible = "ti,ads1000" },
 426         { }
 427 };
 428
 429 MODULE_DEVICE_TABLE(of, ads1100_of_match);
 430
 431 static struct i2c_driver ads1100_driver = {
 432         .driver = {
 433                    .name = "ads1100",
 434                    .of_match_table = ads1100_of_match,
 435                    .pm = pm_ptr(&ads1100_pm_ops),
 436         },
 437         .probe = ads1100_probe,
 438         .id_table = ads1100_id,
 439 };
 440
 441 module_i2c_driver(ads1100_driver);
 442
 443 MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
 444 MODULE_DESCRIPTION("Texas Instruments ADS1100 ADC driver");
 445 MODULE_LICENSE("GPL");